1. Field of the Invention
This invention relates to the field of computer displays and in particular, to a method and apparatus for displaying video data, such as from a television transmission, video tape player, video disc, etc., on a computer display.
2. Background Art
Many personal computers and workstations provide an environment in which one or more computer programs may be displayed in a graphical user interface that provides a multi-window display. A computer program may generate graphical and text display data in selected windows on the display. However, it is also desirable to be able to display information from other sources within windows, such as from video data sources.
In the prior art, video data is processed separately from other computer display data. Computer display data is generated and provided to the display on a first path. A second path is provided for accepting video data from a video source such as a television transmission, video tape player, video disc, etc. The video data is merged with computer display data at a summing node for eventual display on a computer display.
In such prior art schemes, the video data is processed outside the windowing environment that is associated with the interaction, presentation and manipulation of computer display data shown as application program output data. Such data, therefore, cannot be manipulated, resized, moved, etc. within an associated window like computer display data. In addition, video data may not be buffered, in which case it must be displayed at the video data rate, which is typically different than the computer display rate, degrading resolution.
One prior art video processing system is described in Taylor, U.S. Pat. No. 4,148,070. Taylor is directed to a video processing system that uses an analog to digital converter to receive a video signal and convert the signal into a digital form. The digital data is stored in a digital frame store buffer. Addressing means address locations within the frame store to access data. A digital to analog converter receives the data from the frame store and converts the data into analog output for display. The video display circuitry is separate from the computer display circuitry. The system of Taylor is limited to a certain display size and the size of the display cannot be modified. In addition, Taylor is not directed to a computer system that utilizes a windowing environment.
Another prior art system is described in Bennett, et al., U.S. Pat. No. 4,417,276. In Bennett means are provided for continuous digitization of successive video images for storage in computer memory. Compression schemes are included to produce a spatially compressed image to reduce memory requirements. The system of Bennett is a dedicated system for digitizing video data and displaying video data. As such, there is no discussion in Bennett of windows capable of manipulation or of merging video data with non-video computer display data.
Fukushima, et al., U.S. Pat. No. 4,498,081 is directed to a display device for displaying both video and graphic or character images. Fukushima provides a separate video data memory for video information and a separate graphic data memory for graphic information. The outputs of these memories are combined and provided to a display. Fukushima, however, is not directed to the presentation of video data in windows.
An interlace/non-interlace converter is described in Bloom, U.S. Pat. No. 4,698,674. The data converter of Bloom converts interlace formatted data into a non-interlace format for storage and memory. Converter circuitry is coupled between the video data source and the memory associated with a CPU that controls the generation of memory addresses to store the data in interlaced or non-interlaced format. The device permits interlaced or non-interlaced data to be manipulated for eventual display. The device of Bloom provides output to a full screen. Bloom also does not show or teach presentation of video data within windows, or combining of video with computer display data.
It is an object of the present invention to provide a method and apparatus for displaying video data on a computer display in connection with computer display data in a windowing environment.
It is a further object of the present invention to provide a method and apparatus for receiving video data at a video rate and displaying it at a different rate.